Paramphistomosis is a parasitic disease endemic in ruminants nearly worldwide. In the present study, anin vitroscreening of the main anthelmintics used in Mexico was carried out to determine the mean lethal dose for rumen fluke eggs from cattle in a humid, warm region. Rumen flukes were obtained from cattle slaughtered in the states of Tabasco and Chiapas in Mexico. Eggs were collected using a 37-μm sieve and quantified. Then, anin vitroincubation study was performed: 100 eggs were placed into the wells of polystyrene microtiter plates. Anthelmintic products were tested on the eggs at concentrations ranging from 0.0015 to 3.0 mg/ml for rafoxanide, 0.0025 to 10.20 mg/ml for nitroxinil and 0.0015 to 3 mg/ml for closantel to determine the median lethal dose (LD50) and maximum lethal dose (LD99). A control group (water) was included in each plate. Three different species of rumen flukes (Calicophoron brothriophoron,Calicophoron clavulaandParamphistomum cervi) belonging to five isolates were identified. Nitroxinil had the highest efficacy against rumen fluke eggs, with an LD50of 0.11 to 65 μg/ml, whereas rafoxanide showed the lowest efficacy with an LD50ranging from 500 to 1713 μg/ml. Closantel showed high variability in the LD50among the different analysed isolates (17 to 122 μg/ml). The evaluated flukicidal drugs presented differential efficacy against the development of rumen fluke eggs. The efficacy of the drugs will vary depending on the geographical area of origin of the animals.

中文翻译：

---

对从墨西哥潮湿热带地区饲养的牛中回收的瘤胃吸虫卵发育的驱虫药物评估

副寄生虫病是一种几乎在全世界范围内流行于反刍动物的寄生虫病。在本研究中，一体外对墨西哥使用的主要驱虫剂进行了筛选，以确定潮湿、温暖地区牛瘤胃吸虫卵的平均致死剂量。瘤胃吸虫是从墨西哥塔巴斯科州和恰帕斯州屠宰的牛身上获得的。使用 37-μm 筛子收集卵子并进行量化。然后，一个体外进行了孵化研究：将 100 个卵放入聚苯乙烯微量滴定板的孔中。在鸡蛋上测试了驱虫产品，浓度范围为 0.0015 至 3.0 mg/ml 的雷福尼特、0.0025 至 10.20 mg/ml 的硝克尼和 0.0015 至 3 mg/ml 的氯生太，以确定中位致死剂量（LD50) 和最大致死剂量 (LD99）。每个板中包括一个对照组（水）。三种不同种类的瘤胃吸虫（卡利佛龙,棒状花序和鹿副杆菌) 鉴定出属于五个分离株。Nitroxinil 对瘤胃吸虫卵的功效最高，LD50为 0.11 至 65 μg/ml，而雷福尼特的 LD 疗效最低50范围从 500 到 1713 μg/ml。Closantel 在 LD 中表现出高度可变性50在不同的分析分离物（17 至 122 μg/ml）中。评估的杀吸虫药物对瘤胃吸虫卵的发育表现出不同的功效。药物的功效将根据动物的原产地理区域而有所不同。